Pixel structure of image sensor and method of forming same

ABSTRACT

A photo diode includes a pixel unit, a photo conversion layer, and a dielectric layer. The pixel unit includes a pair of pixels. The photo conversion layer is above the pixel unit and has a pair of portions, each of which corresponds to a respective one of the pixels. The dielectric layer is between the portions of the photo conversion layer. A method of manufacturing the photo diode is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/731,474, filed Jun. 5, 2015, which is a divisional of U.S. patentapplication Ser. No. 14/014,488, filed Aug. 30, 2013, all of which areincorporated herein by reference in their entirety.

FIELD

The technology described in this patent document generally relates tosemiconductor processes, and, more particularly, to a photo diode and amethod of forming a photo diode.

BACKGROUND

As photo-electronic technology improves, products using imagetechnology, such as the digital cameras, scanners, and video cameras,have become more popular. In the manufacturing process of image sensors,photo diodes are capable of sensing different colors such as red, green,and blue by means of color filters. Typically, each of the photo diodessenses a specific color only. However, conventional photo diodearchitecture may suffer serious crosstalk issues because light receivedfrom a tilt angle may interfere with adjacent pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-6 are exemplary diagrams during a sequence of processing stagesfor forming a photo diode according to a first embodiment of theinvention.

FIGS. 7-11 are exemplary diagrams during a sequence of processing stagesfor forming a photo diode according to a second embodiment of theinvention.

FIGS. 12-17 are exemplary diagrams during a sequence of processingstages for forming a photo diode according to a third embodiment of theinvention.

FIG. 18 is an exemplary diagram for a photo diode according to a firstembodiment of the invention.

FIG. 19 is an exemplary diagram for a photo diode according to a secondembodiment of the invention.

FIG. 20 is an exemplary diagram for a photo diode according to a thirdembodiment of the invention.

FIG. 21 is a flow chart for forming a photo diode according to a firstexemplary embodiment of the invention.

FIG. 22 is a flow chart for forming a photo diode according to a secondexemplary embodiment of the invention.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, which areillustrated in the accompanying drawings. Wherever possible, the samereference numbers will be used throughout the drawings to refer to thesame or like parts.

FIGS. 1-6 are exemplary diagrams during a sequence of processing stagesfor forming a photo diode according to a first embodiment of theinvention. As shown in FIG. 1, a read circuit 102 over a substrate (notshown) may be provided in a photo diode 100. A capping layer 104 forprotecting vias 107 in the back end of line process may be provided overthe read circuit 102. The capping layer 104 may be, for example, siliconnitride or silicon carbide. The vias 107 may be, for example,aluminum-copper or copper. A first dielectric layer 106 for electricisolation between the first pair of electrodes 110A, 110B and the secondpair of electrodes 112A, 112B and other metal layers (not shown) in theback end of line process may be provided over the capping layer 104. Asecond dielectric layer 108 for electric isolation between theelectrodes 110A, 110B, 112A, 112B may be provided over the firstdielectric layer 106. The dielectric layers 106, 108 may be, forexample, oxide or other isolation materials. The first pair ofelectrodes 110A, 110B and the second pair of electrodes 112A, 112B maybe any metal or alloy, such as, aluminum-copper and copper. The firstpair of electrodes 110A, 110B may correspond to a first pixel 114, andthe second pair of electrodes 112A, 112B may correspond to a secondpixel 116. The first pair of electrodes 110A, 110B and the second pairof electrodes 112A, 112B may be formed by the same conductive layer. Thefirst pair of electrodes 110A, 110B may include a first positiveelectrode 110A and a first negative electrode 110B, and the second pairof electrodes 112A, 112B may include a second positive electrode 112Aand a second negative electrode 112B.

As shown in FIG. 2, a third dielectric layer 202 may be provided on thesecond dielectric layer 108 and the first pair of electrodes 110A, 110Band the second pair of electrodes 112A, 112B. The third dielectric layer202 may be also provided over the substrate (not shown).

As shown in FIG. 3, a mask (not shown) may be used to define an etchingregion for the third dielectric layer 202. A portion of the thirddielectric layer 202 may be removed by, for example, a dry etchingprocess to form a first grid 302 corresponding to the first pixel 114and a second grid 304 corresponding to the second pixel 116. The firstgrid 302 and the second grid 304 may be separated by a portion 306 ofthe third dielectric layer 202.

As shown in FIG. 4, a photo conversion layer 401 may be formed on thesecond dielectric layer 108 and the first pair of electrodes 110A, 110Band the second pair of electrodes 112A, 112B. The portion 306 of thethird dielectric layer 202 defines a first portion 402 of the photoconversion layer 401 corresponding to a first pixel 114 from a secondportion 404 of the photo conversion layer 401 corresponding to thesecond pixel 116. The photo conversion layer 401 may be organic films,such as Phenyl-C61-butyric acid methyl ester (PCBM) orpoly(3-hexylthiophene) (P3HT). The refractive index of the thirddielectric layer 202 is lower than the refractive index of the photoconversion layer 401. For example, the refractive index of the photoconversion layer 401 may be about 1.6 to 2, while the refractive indexof the third dielectric layer 202 may be smaller than 1.5. In anembodiment of the invention, the thickness of the photo conversion layer401 may be 100 nanometers to several micrometers.

As shown in FIG. 5, a color filter layer 501 may be formed over thephoto conversion layer 401. In an embodiment of the invention, a firstportion 502 of the color filter layer 501 corresponding to the firstpixel 114 may be formed by a red filter process; and a second portion504 of the color filter layer 501 corresponding to the second pixel 116may be formed by a green filter process. In an embodiment of theinvention, the thickness of the color filter layer 501 may be 0.3micrometers to 1 micrometers.

As shown in FIG. 6, a micro lens layer 601 may be formed over the colorfilter layer 501. A first portion 602 of the micro lens layer 601 maycorrespond to the first pixel 114, and a second portion 604 of the microlens layer 601 may correspond to the second pixel 116. In an embodimentof the invention, the photo diode 100 is formed. In the first pixel 114,bias voltage between the first pair of electrodes 110A, 110B may beapplied to trigger an electric field that enhances the electrodes 110A,110B in the collection of holes or electrons converted by the firstportion 402 of the photo conversion layer 401. Also, in the second pixel116, bias voltage between the second pair of electrodes 112A, 112B maybe applied to trigger an electric field that enhances the electrodes112A, 112B in the collection of holes or electrons converted by thesecond portion 404 of the photo conversion layer 401.

Light through the first portion 602 of the micro lens layer 601, thefirst portion 502 of the color filter layer 501, and the first portion402 of the photo conversion layer 401 may not pass through the secondportion 404 of the photo conversion layer 401 because the portion 306 ofthird dielectric layer 202 separating the photo conversion layer 401 maychange the direction of light.

Total internal reflection may occur and is a phenomenon that happenswhen a propagating wave strikes a medium boundary at an angle largerthan a particular critical angle with respect to the normal to thesurface. For example, according to the formula

${\theta_{c} = {\arcsin\frac{n_{2}}{n_{1}}}},$assuming that the refractive index (corresponding to n1 in this case) ofthe photo conversion layer 401 is 2 and the refractive index(corresponding to n2 in this case) of the third dielectric layer 202 is1.5, the critical angle may be about 49 degrees.

When light 650 strikes the boundary between the photo conversion layer401 and the portion 306 of the third dielectric layer 202 at an anglelarger than the critical angle (49 degrees) with respect to the normalto the lateral surface 606 of the third dielectric layer 202, light 650cannot pass through the portion 306 of the third dielectric layer 202and is reflected. Therefore, light 650 through the first portion 502 ofthe color filter layer 501 corresponding to the first pixel 114 may notpass through the second portion 404 of the photo conversion layer 401corresponding to the second pixel 116. The second pair of electrodes112A, 112B corresponding to the second pixel 116 may not receive holesor electrons converted from light 650 through the first pixel 114. In anembodiment of the invention, crosstalk of light between the pixels 114,116 in the photo diode 100 may be reduced.

FIGS. 7-11 are exemplary diagrams during a sequence of processing stagesfor forming a photo diode according to a second embodiment of theinvention. As shown in FIG. 7, a read circuit 702 over a substrate (notshown) may be provided in the photo diode 700. A capping layer 704 forprotecting vias 707 in the back end of line process may be provided overthe read circuit 702. The capping layer 704 may be, for example, siliconnitride or silicon carbide. The vias 707 may be, for example,aluminum-copper or copper. A first dielectric layer 706 for electricisolation between bottom electrodes 810, 812 and other metal layers (notshown) in the back end of line process may be provided over the cappinglayer 804. A second dielectric layer 708 for electric isolation betweenthe electrodes 710A, 710B, 712A, 712B may be provided over the firstdielectric layer 706. The dielectric layers 706, 708 may be, forexample, oxide or other isolation materials. The first pair ofelectrodes 710A, 710B and the second pair of electrodes 712A, 712B maybe any metal or alloy, such as, aluminum-copper and copper. The firstpair of electrodes 710A, 710B may correspond to a first pixel 714, andthe second pair of electrodes 712A, 712B may correspond to a secondpixel 716. The first pair of electrodes 710A, 710B and the second pairof electrodes 712A, 712B may be formed by the same conductive layer. Thefirst pair of electrodes 710A, 710B may include a first positiveelectrode 710A and a first negative electrode 710B, and the second pairof electrodes 712A, 712B may include a second positive electrode 712Aand a second negative electrode 712B.

A photo conversion layer 718 may be formed on the dielectric layer 708,the first pair of electrodes 710A, 710B and the second pair ofelectrodes 712A, 712B. The photo conversion layer 718 may be organicfilms, such as Phenyl-C61-butyric acid methyl ester (PCBM) orpoly(3-hexylthiophene) (P3HT).

As shown in FIG. 8, a third dielectric layer 802 may be provided on thephoto conversion layer 718. As shown in FIG. 9, a mask (not shown) maybe used to define an etching region for the third dielectric layer 802.A portion of the third dielectric layer 802 may be removed by, forexample, a dry etching process to form a first grid 902 corresponding tothe first pixel 714 and a second grid 904 corresponding to the secondpixel 716. The first grid 902 and the second grid 904 may be separatedby a portion 906 of the dielectric layer 802.

As shown in FIG. 10, a color filter layer 1001 may be formed on thephoto conversion layer 718. In an embodiment of the invention, a firstportion 1002 of the color filter layer 1001 corresponding to the firstpixel 714 may be formed by a red filter process; and a second portion1004 of the color filter layer 1001 corresponding to the second pixel716 may be formed by a green filter process. In an embodiment of theinvention, the thickness of the color filter layer 1001 may be 0.3micrometers to 1 micrometers.

The portion 906 of the dielectric layer 802 defines the first portion1002 of the color filter layer 1001 corresponding to the first pixel 714from the second portion 1004 of the color filter layer 1001corresponding to the second pixel 716. The refractive index of the thirddielectric layer 802 may be lower than the refractive index of the colorfilter layer 1001. For example, the refractive index of the color filterlayer 1001 may be about 1.6 to 2, while the refractive index of thethird dielectric layer 802 may be smaller than 1.5.

As shown in FIG. 11, a micro lens layer 1101 may be formed over thecolor filter layer 1001. A first portion 1102 of the micro lens layer1101 may correspond to the first pixel 714, and a second portion 1104 ofthe micro lens layer 1101 may correspond to the second pixel 716. In anembodiment of the invention, the photo diode 700 is formed. In the firstpixel 714, bias voltage between the first pair of electrodes 710A, 710Bmay be applied to trigger an electric field that enhances the electrodes710A, 710B in the collection of holes or electrons converted by thephoto conversion layer 718. Also, in the second pixel 716, bias voltagebetween the second pair of electrodes 712A, 712B may be applied totrigger an electric field that enhances the electrodes 712A, 712B in thecollection of holes or electrons converted by the photo conversion layer718.

Light through the first portion 1102 of the micro lens layer 1101 andthe first portion 1002 of the color filter layer 1001 may not passthrough the second portion 1004 of the color filter layer 1001 becausethe portion 906 of third dielectric layer 802 separating the colorfilter layer 1001 may change the direction of light.

Total internal reflection may occur and is a phenomenon that happenswhen a propagating wave strikes a medium boundary at an angle largerthan a particular critical angle with respect to the normal to thesurface. For example, according to the formula

${\theta_{c} = {\arcsin\frac{n_{2}}{n_{1}}}},$assuming that the refractive index (corresponding to n1 in this case) ofthe color filter layer 1001 is 2 and the refractive index (correspondingto n2 in this case) of the third dielectric layer 802 is 1.5, thecritical angle may be about 49 degrees. When light 1150 strikes theboundary between the color filter layer 1001 and the portion 1006 ofthird dielectric layer 802 at an angle larger than the critical angle(49 degrees) with respect to the normal to the lateral surface 1106 ofthe third dielectric layer 802, light 1150 cannot pass through theportion 1006 of third dielectric layer 802 and is reflected.

Therefore, light 1150 through the first portion 1002 of the color filterlayer 1001 corresponding to the first pixel 714 may not pass through aportion of photo conversion layer 718 corresponding to the second pixel716. The second pair of electrodes 712A, 712B corresponding to thesecond pixel 716 may not receive holes or electrons converted from light1150 through the first pixel 714. In an embodiment of the invention,crosstalk of light between the pixels 714, 716 in the photo diode 700may be reduced.

FIGS. 12-17 are exemplary diagrams during a sequence of processingstages for forming a photo diode according to a third embodiment of theinvention. As shown in FIG. 12, a read circuit 1202 over a substrate(not shown) may be provided in a photo diode 1200. A capping layer 1204for protecting vias 1207 in the back end of line process may be providedover the read circuit 1202. The capping layer 1204 may be, for example,silicon nitride or silicon carbide. The vias 1207 may be, for example,aluminum-copper or copper. A first dielectric layer 1206 for electricisolation between the first pair of electrodes 1210A, 1210B and thesecond pair of electrodes 1212A, 1212B and other metal layers (notshown) in the back end of line process may be provided over the cappinglayer 1204. A second dielectric layer 1208 for electric isolationbetween the electrodes 1210A, 1210B, 1212A, 1212B may be provided overthe first dielectric layer 1206. The dielectric layers 1206, 1208 maybe, for example, oxide or other isolation materials. The first pair ofelectrodes 1210A, 1210B and the second pair of electrodes 1212A, 1212Bmay be any metal or alloy, such as, aluminum-copper and copper. Thefirst pair of electrodes 1210A, 1210B may correspond to a first pixel1214, and the second pair of electrodes 1212A, 1212B may correspond to asecond pixel 1216. The first pair of electrodes 1210A, 1210B and thesecond pair of electrodes 1212A, 1212B may be formed by the sameconductive layer. The first pair of electrodes 1210A, 1210B may includea first positive electrode 1210A and a first negative electrode 1210B,and the second pair of electrodes 1212A, 1212B may include a secondpositive electrode 1212A and a second negative electrode 1212B.

As shown in FIG. 13, a third dielectric layer 1302 may be provided onthe second dielectric layer 1208 and the first pair of electrodes 1210A,1210B and the second pair of electrodes 1212A, 1212B. The thirddielectric layer 1302 may be also provided over the substrate (notshown).

As shown in FIG. 14, a mask (not shown) may be used to define an etchingregion for the third dielectric layer 1302. A portion of the thirddielectric layer 1302 may be removed by, for example, a dry etchingprocess to form a first grid 1402 corresponding to the first pixel 1214and a second grid 1404 corresponding to the second pixel 1216. The firstgrid 1402 and the second grid 1404 may be separated by a portion 1406 ofthe third dielectric layer 1302.

As shown in FIG. 15, a photo conversion layer 1501 may be formed on thesecond dielectric layer 1208 and the first pair of electrodes 1210A,1210B and the second pair of electrodes 1212A, 1212B. The portion 1406of the third dielectric layer 1302 defines a first portion 1502 of thephoto conversion layer 1501 corresponding to the first pixel 1214 from asecond portion 1504 of the photo conversion layer 1501 corresponding tothe second pixel 1216. The photo conversion layer 1501 may be organicfilms, such as Phenyl-C61-butyric acid methyl ester (PCBM) orpoly(3-hexylthiophene) (P3HT). The refractive index of the thirddielectric layer 1302 is lower than the refractive index of the photoconversion layer 1501. For example, the refractive index of the photoconversion layer 1501 may be about 1.6 to 2, while the refractive indexof the third dielectric layer 1302 may be smaller than 1.5. In anembodiment of the invention, the thickness of the photo conversion layer1501 may be 100 nanometers to several micrometer.

As shown in FIG. 16, a color filter layer 1601 may be formed on thephoto conversion layer 1501. In an embodiment of the invention, a firstportion 1602 of the color filter layer 1601 corresponding to the firstpixel 1214 may be formed by a red filter process; and a second portion1604 of the color filter layer 1601 corresponding to the second pixel1216 may be formed by a green filter process. In an embodiment of theinvention, the thickness of the color filter layer 1601 may be 0.3micrometers to 1 micrometers.

The portion 1406 of the third dielectric layer 1302 defines a firstportion 1602 of the color filter layer 1601 corresponding to the firstpixel 1214 from a second portion 1604 of the color filter layer 1601corresponding to the second pixel 1216. The refractive index of thethird dielectric layer 1302 is lower than the refractive index of thecolor filter layer 1601. For example, the refractive index of the colorfilter layer 1601 may be about 1.6 to 2, while the refractive index ofthe third dielectric layer 1302 may be smaller than 1.5.

As shown in FIG. 17, a micro lens layer 1701 is formed over the colorfilter layer 1601. A first portion 1702 of the micro lens layer 1701 maycorrespond to a first pixel 1214, and the second portion 1704 of themicro lens layer 1701 may correspond to a second pixel 1216. In anembodiment of the invention, the photo diode 1200 is formed. In thefirst pixel 1214, bias voltage between the first pair of electrodes1210A, 1210B may be applied to trigger an electric field that enhancesthe electrodes 1210A, 1210B in the collection of holes or electronsconverted by the first portion 1502 of the photo conversion layer 1501.Also, in the second pixel 716, bias voltage between the second pair ofelectrodes 1212A, 1212B may be applied to trigger an electric field thatenhances the electrodes 1212A, 1212B in the collection of holes orelectrons converted by the second portion 1504 of the photo conversionlayer 1501.

Light through the first portion 1702 of the micro lens layer 1701, thefirst portion 1602 of the color filter layer 1601 and the first portion1502 of the photo conversion layer 1501 may not pass through the secondportion 1504 of the photo conversion layer 1501 because the portion 1406of third dielectric layer 1302 separating the photo conversion layer1501 may change the direction of the light.

Total internal reflection may occur and is a phenomenon that happenswhen a propagating wave strikes a medium boundary at an angle largerthan a particular critical angle with respect to the normal to thesurface. For example, according to the formula

${\theta_{c} = {\arcsin\frac{n_{2}}{n_{1}}}},$assuming that the refractive index (corresponding to n1 in this case) ofthe photo conversion layer 1501 is 2 and the refractive index(corresponding to n2 in this case) of the third dielectric layer 1302 is1.5, the critical angle may be about 49 degrees. When light 1750 strikesthe boundary between the photo conversion layer 1501 and the portion1406 of third dielectric layer 1302 at an angle larger than the criticalangle (49 degrees) with respect to the normal to the lateral surface1706 of the third dielectric layer 1302, light 1750 cannot pass throughthe portion 1406 of third dielectric layer 1302 and is reflected.Therefore, light 1750 through the first portion 1502 of the color filterlayer 1501 corresponding to the first pixel 1214 may not pass throughthe second portion 1504 of the photo conversion layer 1501 correspondingto the second pixel 1216. The second pair of electrodes 1212A, 1212Bcorresponding to the second pixel 1216 may not receive holes orelectrons converted from light 1750 through the first pixel 1214. In anembodiment of the invention, crosstalk of light between the pixels 1214,1216 in the photo diode 1200 may be reduced.

Light through the first portion 1702 of the micro lens layer 1701 andthe first portion 1602 of the color filter layer 1601 may not passthrough the second portion 1604 of the color filter layer 1601 becausethe portion 1406 of third dielectric layer 1302 separating the colorfilter layer 1001 may change the direction of light.

In an embodiment of the invention, according to the formula

${\theta_{c} = {\arcsin\frac{n_{2}}{n_{1}}}},$assuming that the refractive index (corresponding to n1 in this case) ofthe color filter layer 1601 is 2 and the refractive index (correspondingto n2 in this case) of the third dielectric layer 1302 is 1.5, thecritical angle may be about 49 degrees. When light 1760 strikes theboundary between the color filter layer 1601 and the portion 1406 ofthird dielectric layer 1302 at an angle larger than the critical angle(49 degrees) with respect to the normal to the lateral surface 1706 ofthe third dielectric layer 1302, light 1760 cannot pass through theportion 1406 of the third dielectric layer 1302 and is reflected.

Therefore, light 1760 through the first portion 1602 of the color filterlayer 1601 corresponding to the first pixel 1214 may not pass throughthe second portion 1504 of the photo conversion layer 1501 correspondingto the second pixel 1216. The second pair of electrodes 1212A, 1212Bcorresponding to the second pixel 1216 may not receive holes orelectrons converted from light 1760 through the first pixel 1214. In anembodiment of the invention, crosstalk of light between the pixels 1214,1216 in the photo diode 1200 may be also reduced.

FIG. 18 is an exemplary diagram for a photo diode according to a firstembodiment of the invention. As shown in FIG. 18, a photo diode 1800 mayinclude a substrate (not shown), a photo conversion layer 1802, a colorfilter layer 1804 and a dielectric layer 1806. The photo conversionlayer 1802 is disposed over the substrate (not shown). The color filterlayer 1804 is disposed over the photo conversion layer 1802. A portion1830 of the dielectric layer 1806 defines a first portion 1808 of thephoto conversion layer 1802 corresponding to a first pixel 1812 from asecond portion 1810 of the photo conversion layer 1802 corresponding toa second pixel 1814. The refractive index of the dielectric layer 1806may be lower than the refractive index of the photo conversion layer1802.

In an embodiment of the invention, the photo diode 1800 further includesa first pair of electrodes 1816A, 1816B and a second pair of electrodes1818A, 1818B disposed over the substrate (not shown). The first pair ofelectrodes 1816A, 1816B may correspond to the first pixel 1812, and thesecond pair of electrodes 1818A, 1818B may correspond to the secondpixel 1814. In an embodiment of the invention, the photo conversionlayer 1802 is an organic film layer. In an embodiment of the invention,the photo diode 1800 further includes a read out circuit 1822. The readout circuit 1822 is disposed over the substrate (not shown). In anembodiment of the invention, the photo diode 1800 further includes amicro lens layer 1824. The micro lens layer 1824 is disposed over thecolor filter layer 1804. In an embodiment of the invention, a firstportion 1826 of the color filter layer 1804 corresponding to the firstpixel 1812 is a red filter, and a second portion 1828 of the colorfilter layer 1804 corresponding to the second pixel 1814 is a greenfilter. In an embodiment of the invention, the dielectric layer 1806includes a first grid corresponding to the first pixel 1812 and a secondgrid corresponding to the second pixel 1814. In an embodiment of theinvention, the first pair of electrodes 1816A, 1816B may include a firstpositive electrode 1816A and a first negative electrode 1816B, and thesecond pair of electrodes 1818A, 1818B may include a second positiveelectrode 1818A and a second negative electrode 1818B.

FIG. 19 is an exemplary diagram for a photo diode according to a secondembodiment of the invention. As shown in FIG. 19, another photo diode1900 includes a substrate (not shown), a photo conversion layer 1902, acolor filter layer 1904 and a dielectric layer 1906. The photoconversion layer 1902 is disposed over the substrate (not shown). Thecolor filter layer 1904 is disposed over the photo conversion layer1902. A portion 1926 of the dielectric layer 1906 defines a firstportion 1908 of the color filter layer 1904 corresponding to a firstpixel 1912 from a second portion 1910 of the color filter layer 1904corresponding to a second pixel 1914. The refractive index of thedielectric layer 1906 is lower than the refractive index of the colorfilter layer 1904.

In an embodiment of the invention, the photo diode 1900 further includesa first pair of electrodes 1916A, 1916B and a second pair of electrodes1918A, 1918B disposed over the substrate (not shown). The first pair ofelectrodes 1916A, 1916B may correspond to the first pixel 1912, and thesecond pair of electrodes 1918A, 1918B may correspond to the secondpixel 1914. In an embodiment of the invention, the photo conversionlayer 1902 is an organic film layer. In an embodiment of the invention,the photo diode 1900 further includes a read out circuit 1922. The readout circuit 1922 is disposed over the substrate (not shown). In anembodiment of the invention, the photo diode 1900 further includes amicro lens layer 1924. The micro lens layer 1924 is disposed over thecolor filter layer 1904. In an embodiment of the invention, the firstportion 1908 of the color filter layer 1904 corresponding to the firstpixel 1912 is a red filter, and the second portion 1910 of the colorfilter layer 1904 corresponding to the second pixel 1914 is a greenfilter. In an embodiment of the invention, the dielectric layer 1906includes a first grid corresponding to the first pixel 1912 and a secondgrid corresponding to the second pixel 1914. In an embodiment of theinvention, the first pair of electrodes 1916A, 1916B may include a firstpositive electrode 1916A and a first negative electrode 1916B, and thesecond pair of electrodes 1918A, 1918B may include a second positiveelectrode 1918A and a second negative electrode 1918B.

FIG. 20 is an exemplary diagram for a photo diode according to a thirdembodiment of the invention. As shown in FIG. 20, another photo diode2000 includes a substrate (not shown), a photo conversion layer 2002, acolor filter layer 2004 and a dielectric layer 2006. The photoconversion layer 2002 is disposed over the substrate (not shown). Thecolor filter layer 2004 is disposed over the photo conversion layer2002. A portion 2020 of the dielectric layer 2006 defines a firstportion 2008 of the photo conversion layer 2002 corresponding to a firstpixel 2012 from a second portion 2010 of the photo conversion layer 2002corresponding to a second pixel 2014. The refractive index of thedielectric layer 2006 is lower than the refractive index of the photoconversion layer 2002 and the refractive index of the color filter layer2004. The portion 2020 of the dielectric layer 2006 also defines a firstportion 2016 of the color filter layer 2004 corresponding to the firstpixel 2012 from a second portion 2018 of the color filter layer 2004corresponding to the second pixel 2014.

In an embodiment of the invention, the photo diode 2000 further includesa first pair of electrodes 2024A, 2024B and a second pair of electrodes2026A, 2026B disposed over the substrate (not shown). The first pair ofelectrodes 2024A, 2024B may correspond to the first pixel 2012, and thesecond pair of electrodes 2026A, 2026B may correspond to the secondpixel 2014. In an embodiment of the invention, the photo conversionlayer 2002 is an organic film layer. In an embodiment of the invention,the photo diode 2000 further includes a read out circuit 2030. The readout circuit 2030 is disposed over the substrate (not shown). In anembodiment of the invention, the photo diode 2000 further includes amicro lens layer 2032. The micro lens layer 2032 is disposed over thecolor filter layer 2004. In an embodiment of the invention, a firstportion 2016 of the color filter layer 2004 corresponding to the firstpixel 2012 is a red filter, and the second portion 2018 of the colorfilter layer 2004 corresponding to the second pixel 2014 is a greenfilter. In an embodiment of the invention, the dielectric layer 2006includes two grids. Each of the grids the dielectric layer 2006respectively may correspond to the first pixel 2012 and the second pixel2014. In an embodiment of the invention, the first pair of electrodes2024A, 2024B may include a first positive electrode 2024A and a firstnegative electrode 2024B, and the second pair of electrodes 2026A, 2026Bmay include a second positive electrode 2026A and a second negativeelectrode 2026B.

FIG. 21 is a flow chart for forming a photo diode according to a firstexemplary embodiment of the invention. As shown in FIG. 21, the method2100 for forming a photo diode is provided. The method 2100 may includethe following procedures: forming a first pair of electrodes and asecond pair of electrodes over a substrate by using a conductive layer(S2102); forming a dielectric layer over the substrate (S2104);patterning the dielectric layer over the substrate (S2106); forming aphoto conversion layer over the substrate (S2108); and forming a colorfilter layer over the photo conversion layer, wherein at least a portionof the dielectric layer separates a first portion of the color filterlayer corresponding to a first pixel from a second portion of the colorfilter layer corresponding to a second pixel, and a refractive index ofthe dielectric layer is lower than a refractive index of the colorfilter layer, wherein the first pair of electrodes corresponds to thefirst pixel and the second pair of electrodes corresponds to the secondpixel (S2110).

FIG. 22 is a flow chart for forming a photo diode according to a secondexemplary embodiment of the invention. As shown in FIG. 22, the method2200 for forming a photo diode is provided. The method 2200 may includethe following procedures: forming a first pair of electrodes and asecond pair of electrodes over a substrate by using a conductive layer(S2202); forming a dielectric layer over the substrate (S2204);patterning the dielectric layer over the substrate (S2206); forming aphoto conversion layer over the substrate (S2208); and forming a colorfilter layer over the photo conversion layer, wherein at least a portionof the dielectric layer separates a first portion of the photoconversion layer corresponding to a first pixel from a second portion ofthe photo conversion layer corresponding to a second pixel, and arefractive index of the dielectric layer is lower than a refractiveindex of the photo conversion layer, wherein the first pair ofelectrodes corresponds to the first pixel and the second pair ofelectrodes corresponds to the second pixel (S2210).

An exemplary photo diode comprises a pixel unit that includes a pair ofpixels, a photo conversion layer that is above the pixel unit and thathas a pair of portions, each of which corresponds to a respective one ofthe pixels, and a dielectric layer that is between the portions of thephoto conversion layer.

Another exemplary photo diode comprises a pixel unit that includes apair of pixels, a color filter that is above the pixel unit and that hasa pair of portions, each of which corresponds to a respective one of thepixels, and a dielectric layer that is between the portions of the colorfilter.

An exemplary method of manufacturing a photo diode comprises forming apixel unit that includes a pair of pixels, forming a dielectric layerabove the pixel unit, forming above the pixel unit a photo conversionlayer and a color filter, each of which has a pair of portions thatrespectively correspond to the pixels, and patterning the dielectriclayer such that the dielectric layer is between the portions of at leastone of the photo conversion layer and the color filter.

This written description uses examples to disclose the disclosure,include the best mode, and also to enable a person skilled in the art tomake and use the disclosure. The patentable scope of the disclosure mayinclude other examples that occur to those skilled in the art.

One skilled in the relevant art will recognize that the variousembodiments may be practiced without one or more of the specificdetails, or with other replacement and/or additional methods, materials,or components. Well-known structures, materials, or operations may notbe shown or described in detail to avoid obscuring aspects of variousembodiments of the disclosure. Various embodiments shown in the figuresare illustrative example representations and are not necessarily drawnto scale. Particular features, structures, materials, or characteristicsmay be combined in any suitable manner in one or more embodiments.Various additional layers and/or structures may be included and/ordescribed features may be omitted in other embodiments. Variousoperations may be described as multiple discrete operations in turn, ina manner that is most helpful in understanding the disclosure. However,the order of description should not be construed as to imply that theseoperations are necessarily order dependent. In particular, theseoperations need not be performed in the order of presentation.Operations described herein may be performed in a different order, inseries or in parallel, than the described embodiment. Various additionaloperations may be performed and/or described. Operations may be omittedin additional embodiments.

This written description and the following claims may include terms,such as left, right, top, bottom, over, under, upper, lower, first,second, etc. that are used for descriptive purposes only and are not tobe construed as limiting. For example, terms designating relativevertical position may refer to a situation where a device side (oractive surface) of a substrate or integrated circuit is the “top”surface of that substrate; the substrate may actually be in anyorientation so that a “top” side of a substrate may be lower than the“bottom” side in a standard terrestrial frame of reference and may stillfall within the meaning of the term “top.” The term “on” as used herein(including in the claims) may not indicate that a first layer “on” asecond layer is directly on and in immediate contact with the secondlayer unless such is specifically stated; there may be a third layer orother structure between the first layer and the second layer on thefirst layer. The embodiments of a device or article described herein maybe manufactured, used, or shipped in a number of positions andorientations. Persons skilled in the art will recognize variousequivalent combinations and substitutions for various components shownin the figures.

What is claimed is:
 1. A photo diode comprising: a pixel unit including a pair of pixels; a photo conversion layer above the pixel unit and having a pair of portions, each of which corresponds to a respective one of the pixels; a dielectric layer between the portions of the photo conversion layer, the dielectric layer extending along a sidewall of the photo conversion layer from a bottommost surface of the photo conversion layer to at least a topmost surface of the photo conversion layer; and a color filter above the photo conversion layer and having a pair of portions, each of which corresponds to a respective one of the pixels, wherein the dielectric layer is further between the portions of the color filter.
 2. The photo diode of claim 1, wherein the dielectric layer has a refractive index lower than a refractive index of the color filter.
 3. The photo diode of claim 1, wherein the dielectric layer has a refractive index lower than a refractive index of the photo conversion layer.
 4. The photo diode of claim 1, wherein at least one of the pixels includes a pair of electrodes spaced apart from each other in a horizontal direction.
 5. The photo diode of claim 1, further comprising a micro lens unit above the photo conversion layer and including a pair of micro lens, each of which corresponds to a respective one of the pixels.
 6. The photo diode of claim 1, further comprising a read circuit and a via unit between the pixel unit and the read circuit.
 7. The photo diode of claim 1, wherein a thickness of the color filter is between 0.3 μm and 1 μm.
 8. The photo diode of claim 1, wherein the photo conversion layer is an organic film.
 9. A semiconductor structure comprising: a pixel unit including a pair of pixels; a first pair of electrodes corresponding to a first pixel of the pair of pixels, the first pair of electrodes being spaced apart from each other in a lateral direction; a first photo conversion layer corresponding to the first pixel of the pair of pixels; a first color filter corresponding to the first pixel of the pair of pixels, the first photo conversion layer being interposed between the first pair of electrodes and the first color filter; a second photo conversion layer corresponding to a second pixel of the pair of pixels; a second color filter corresponding to the second pixel of the pair of pixels; and a dielectric layer between the first color filter and the second color filter, and between the first photo conversion layer and the second photo conversion layer.
 10. The semiconductor structure of claim 9, wherein the dielectric layer has a refractive index lower than a refractive index of the first photo conversion layer and a refractive index of the second photo conversion layer.
 11. The semiconductor structure of claim 9, wherein the dielectric layer has a refractive index lower than a refractive index of the first color filter and a refractive index of the second color filter.
 12. The semiconductor structure of claim 9, further comprising a micro lens unit above the first color filter and the second color filter, the micro lens unit including a pair of micro lenses, each of which corresponds to a respective one of the pair of pixels.
 13. The semiconductor structure of claim 9, further comprising a read circuit and a via unit between the pixel unit and the read circuit.
 14. The semiconductor structure of claim 9, further comprising a second pair of electrodes corresponding to the second pixel of the pair of pixels, the second pair of electrodes being spaced apart from each other in the lateral direction, the second photo conversion layer being interposed between the second pair of electrodes and the second color filter.
 15. The semiconductor structure of claim 9, wherein a refractive index of the dielectric layer is less than 1.5.
 16. A semiconductor structure comprising: a pixel unit including a pair of pixels; a photo conversion layer and a color filter, each of the photo conversion layer and the color filter having a pair of portions that respectively correspond to the pair of pixels; a plurality of electrodes having a first pair of electrodes corresponding to a first pixel of the pair of pixels and a second pair of electrodes corresponding to a second pixel of the pair of pixels, the photo conversion layer being interposed between the plurality of electrodes and the color filter; and a dielectric layer between the pair of portions of the photo conversion layer, wherein the dielectric layer is at least as thick as the photo conversion layer, and wherein the dielectric layer is further between the pair of portions of the color filter.
 17. The semiconductor structure of claim 16, wherein the dielectric layer has a refractive index lower than a refractive index of at least one of the photo conversion layer and the color filter.
 18. The semiconductor structure of claim 16, wherein a refractive index of the color filter is between about 1.6 and about
 2. 19. The semiconductor structure of claim 16, wherein a refractive index of the photo conversion layer is between about 1.6 and about
 2. 20. The semiconductor structure of claim 16, further comprising a micro lens layer over the color filter, the micro lens layer being in physical contact with the dielectric layer. 